Transfer tool

ABSTRACT

Provided a transfer tool including a substantially strip-shaped frame, a wrist-side slider to be attached to a wrist of a robot, provided on one side of the frame in a thickness direction in a manner capable of moving along a longitudinal direction of the frame, a workpiece-side slider provided on another side of the frame in the thickness direction in a manner capable of moving along the longitudinal direction of the frame, and a distal-end swing shaft attached to the workpiece-side slider, where the distal-end swing shaft includes a workpiece support section supported by the workpiece-side slider in a manner capable of swinging around an axis line extending in a width direction of the frame, the workpiece support section being for supporting a workpiece, and an actuator attached to the workpiece-side slider, the actuator being for causing the workpiece support section to swing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Application No.2017-023887, the content of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a transfer tool.

BACKGROUND ART

Conventionally, to increase the speed of transfer of a workpiece betweenpress devices and to extend the reach, a transfer tool configured from aslide mechanism which is attached to a tip of a wrist of an articulatedrobot and which linearly moves a workpiece in one direction is known(for example, see PTL 1).

The transfer tool described in PTL 1 includes, on front and backsurfaces of a strip-shaped frame, two sliders which are supported in amanner capable of linearly moving along a longitudinal direction of theframe and which are coupled to each other by a belt.

With this transfer tool, when a wrist-side slider fixed to a wrist of anarticulated robot is driven in one direction along the longitudinaldirection of the frame, a workpiece-side slider supporting a workpieceis moved in the opposite direction, and thus, transfer of the workpiecemay be performed at a high speed, and also, the reach may be extended tothe extent of a movable range of each slider, and a stroke two times themovable range of each slider may be obtained.

Furthermore, the transfer tool in PTL 1 includes, at the workpiece-sideslider, a distal-end swing shaft for causing a workpiece to swing aroundan axis line extending in a width direction of the frame. By causing thedistal-end swing shaft to operate, the attitude of a supported workpiecemay be changed without moving the frame of the transfer tool.

CITATION LIST Patent Literature

{PTL 1}

U.S. Patent Application Publication No. 2012/239184

SUMMARY OF INVENTION

An aspect of the present invention provides a transfer tool including asubstantially strip-shaped frame, a wrist-side slider to be attached toa wrist of a robot, provided on one side of the frame in a thicknessdirection in a manner capable of moving along a longitudinal directionof the frame, a workpiece-side slider provided on another side of theframe in the thickness direction in a manner capable of moving along thelongitudinal direction of the frame, and a distal-end swing shaftattached to the workpiece-side slider. The distal-end swing shaftincludes a workpiece support section that is for supporting a workpieceand that is supported by the workpiece-side slider in a manner capableof swinging around an axis line extending in a width direction of theframe, and an actuator that is attached to the workpiece-side slider andthat is for causing the workpiece support section to swing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a robot system to which a transfertool according to an embodiment of the present invention is attached.

FIG. 2 is a perspective view showing the transfer tool in FIG. 1 fromthe side of a wrist-side slider.

FIG. 3 is a perspective view showing the transfer tool in FIG. 1 fromthe side of a workpiece-side slider.

FIG. 4 is a front view showing a distal-end swing shaft provided on theworkpiece-side slider of the transfer tool in FIG. 1.

FIG. 5 is a plan view, partly broken away, showing the distal-end swingshaft in FIG. 2.

FIG. 6 is a perspective view describing supply and removal of aworkpiece to and from a press device by the robot system in FIG. 1.

FIG. 7 is a perspective view showing an example of a tool that isattached to the transfer tool in FIG. 1.

FIG. 8 is a front view showing an operation range of an articulatedrobot where an angle of a workpiece is changed by the distal-end swingshaft of the transfer tool in FIG. 1.

FIG. 9 is a front view showing the operation range of the articulatedrobot where an angle of a workpiece is changed at the transfer tool inFIG. 1, without the use of the distal-end swing shaft.

FIG. 10 is a perspective view showing an example of an interface portionprovided on both ends of a shaft forming the distal-end swing shaft ofthe transfer tool in FIG. 1.

FIG. 11 is a perspective view showing another example of the interfaceportion in FIG. 10.

FIG. 12 is a vertical cross-sectional view showing an example ofattachment of the interface portion in FIG. 10 to the shaft.

DESCRIPTION OF EMBODIMENTS

A transfer tool 1 according to an embodiment of the present inventionwill be described below with reference to the drawings.

As shown in FIG. 1, the transfer tool 1 according to the presentembodiment is a device of a slide arm type which is attached to a tip ofthe wrist of an articulated robot (robot) 30.

For example, as shown in FIG. 1, the articulated robot 30 includes abase 3 fixed to a support base 2, a swivel base 4 supported in a mannercapable of rotating around a horizontal first axis line A horizontal toone side surface of the base 3, a first arm 5 supported in a mannercapable of swinging around a second axis line B perpendicular to an axisline (not shown) parallel to and separated from the first axis line A, asecond arm 6 supported in a manner capable of linearly moving in alongitudinal direction of the first arm 5, and a wrist unit (wrist) 7disposed at a tip of the second arm 6.

That is, the articulated robot 30 includes a first shaft J1 for causingthe swivel base 4 to rotate around the first axis line A with respect tothe base 3, a second shaft J2 for causing the first arm 5 to swingaround the second axis line B with respect to the swivel base 4, and athird shaft J3 for causing the second arm 6 to linearly move in thelongitudinal direction of the first arm 5 with respect to the first arm5.

As for the wrist unit 7, it is enough if two or more rotation shaftswhich rotate around axis lines C, D, E intersecting with one another areprovided.

The wrist unit 7 includes three rotation shafts (fourth shaft J4, fifthshaft J5, and sixth shaft J6) which rotate around the perpendicular axislines C, D, E, and a face plate 8 which is disposed to fix a tool or thelike to the rotation shaft J6 at a terminal. The fourth shaft J4 causesa first wrist housing 9 to rotate, with respect to the second arm 6,around a fourth axis line (rotation shaft) C parallel to thelongitudinal direction of the first arm 5, the fifth shaft J5 causes asecond wrist housing 10 to rotate around a fifth axis line (rotationshaft) D perpendicular to the fourth axis line C, and the sixth shaft J6causes the face plate 8 to rotate around a sixth axis line (rotationshaft) E perpendicular to the fifth axis line D. In the drawing,reference signs 11 to 16 indicate motors of the first shaft J1 to thesixth shaft J6, respectively.

The first shaft J1 causes the swivel base 4 to rotate around thehorizontal first axis line A, and thus, causes the swivel base 4 and thefirst arm 5 attached to the swivel base 4 to the wrist unit 7 to swinglike a pendulum. An operation range of such a pendulum-like motion is ator below a substantially horizontal plane including the first axis lineA. In the case of transferring a workpiece (not shown) by thependulum-like motion, because gravity constantly acts in the directionof aiding acceleration or deceleration, the swinging operation due tooperation of the first shaft J1 may be performed at a high speed andwith little energy.

The second shaft J2 is capable of changing a tilt of the first arm 5with respect to the swivel base 4. The third shaft J3 is capable ofcausing the second arm 6 to linearly move with respect to the first arm5, and of extending or shortening the length of the entire arm formedfrom the first arm 5 and second arm 6.

That is, the wrist unit 7 may be arranged at an arbitrary position inthe operation range by the first shaft J1 to the third shaft J3.Moreover, the attitude of a workpiece attached to the face plate 8 maybe arbitrarily adjusted by the fourth shaft J4 to the sixth shaft J6.

The transfer tool 1 according to the present embodiment includes a frame18 which is strip-shaped (rectangular flat plate shape), and two sliders19, 20 which are disposed on both sides of the frame 18 in a thicknessdirection.

As shown in FIGS. 2 and 3, the two sliders 19, 20 are supported on frontand back surfaces of the frame 18 in a manner capable of moving in alongitudinal direction along guide rails 31 disposed along alongitudinal direction of the frame 18. Furthermore, the two sliders 19,20 are coupled by a belt 21 which is wound around pulleys 32 which aresupported at both ends of the frame 18 in the longitudinal direction ina manner capable of rotating around parallel axis lines.

A rack gear 33 is fixed on one end surface of the frame 18 in a widthdirection, along the longitudinal direction. As shown in FIG. 3, therack gear 33 is meshed with a pinion gear 34 of a motor 22 attached tothe slider (wrist-side slider) 19. When the slider 19 is moved in onedirection along the longitudinal direction on the front surface of theframe 18 by the motor 22 being driven, the other slider (workpiece-sideslider) 20 coupled by the belt 21 is pulled by the belt 21 and is movedin the other direction along the longitudinal direction on the back sideof the frame 18. That is, the two sliders 19, 20 are to relatively movein opposite directions along the longitudinal direction of the frame 18.

The slider 19 is fixed to the sixth shaft J6 of the wrist unit 7. Asshown in FIGS. 4 and 5, the other slider 20 includes a workpiece supportsection 36 to which a tool S (see FIGS. 6 and 7) including a pluralityof suction pads 35 for sticking to a workpiece is to be attached, and adistal-end swing shaft 37 for causing the workpiece support section 36to swing around an axis line F extending in the width direction of theframe 18.

The workpiece support section 36 includes a straight rod-shaped shaft 38attached to the slider 20 in a manner capable of rotating around theaxis line F, and two interface portions 39, 40 fixed on both ends of theshaft 38, as shown in FIG. 10 or 11, for example. The two interfaceportions 39, 40 include attachment surfaces 41 which are parallel toeach other. Accordingly, angle alignment does not have to be performedat the time of attaching the tool S to the interface portions 39, 40,and attachment can be easily performed.

As shown in FIGS. 4 and 5, the distal-end swing shaft 37 includes amotor (actuator) 42, a reducer (actuator) 43 for reducing the speed ofrotation of the motor 42, and a pair of gears (power transmissionsection, actuator) 44, 45 for transmitting an output torque of thereducer 43 to the shaft 38. An output shaft of the reducer 43, and abearing 46 for rotatably supporting the pair of gears 44, 45 and theshaft 38 are housed in a gearbox 47, and are collectively lubricated.

The gearbox 47 is fixed to the slider 20, and the motor 42 is fixed tothe gearbox 47 via the reducer 43. The motor 42 is disposed in parallelto the axis line F of the shaft 38. For example, the pair of gears 44,45 are spur gears, and are a drive gear 44 fixed to the output shaft ofthe reducer 43, and a driven gear 45 fixed to the shaft 38. A diameterof the driven gear 45 is sufficiently larger than that of the drive gear44, and the speed of rotation of the drive gear 44 is thus reduced andis transmitted to the shaft 38.

As shown in FIG. 6, the tool S includes a strut portion 48 fixed to eachof the pair of interface portions 39, 40 on both ends of the shaft 38,and a plurality of branch portions 49 branched and extending from thestrut portion 48, and a plurality of suction pads 35 are disposed ateach branch portion 49 while facing the same direction.

For example, as shown in FIG. 7, the tool S supplies a flat plate-shapedworkpiece W to a press device 24, 25, and sticks to or releases theworkpiece W by the suction pads 35 at the time of removing the workpieceW processed by the press device 24, 25.

Furthermore, as shown in FIG. 1, the articulated robot 30 includes atilted coupling member 23 for fixing together at a predetermined tiltangle the face plate 8 of the wrist unit 7 and one of the sliders(slider 19) to be fixed to the face plate 8.

The tilted coupling member 23 causes the first arm 5 to swing around thesecond axis line B by a predetermined angle, and couples the sixth shaftJ6 of the wrist unit 7 and the transfer tool 1 in such a way that thewidth direction and the longitudinal direction of the transfer tool 1become substantially horizontal when the wrist unit 7 is made straight,that is, in a state where the fourth axis line C and the sixth axis lineE are on one straight line.

An effect of the transfer tool 1 according to the present embodimentconfigured in the above manner will be particularly described for a casewhere supply and removal of a workpiece W are performed between twopress devices 24, 25 which are adjacent to each other with a gaptherebetween, as in the case of a press machine system 50 shown in FIG.6.

As shown in FIG. 1, the articulated robot 30 causes the first arm 5 toswing around the second axis line B by a predetermined angle, andthereby arranges the frame 18 of the transfer tool 1 at a substantiallyhorizontal attitude. At this time, the center of the transfer tool 1 inthe width direction is to be arranged on a straight line (press centerline) P connecting centers of the press devices 24, 25.

Next, as shown in FIG. 6, the swivel base 4 is rotated in one directionaround the first axis line A with respect to the base 3, the first arm 5and the second arm 6 are moved like a pendulum, and each rotation shaftJ4, J5, J6 of the wrist unit 7 is operated, and the transfer tool 1thereby moves along the press center line P while maintaining thesubstantially horizontal attitude and maintaining the longitudinaldirection and the width direction at constant directions. At this time,the motor 22 of the transfer tool 1 is operated, and the two sliders 19,20 are moved relative to each other in such a way that the frame 18extends forward in the swing direction of the first arm 5.

Accordingly, it is possible to insert only the transfer tool 1 into oneof the press devices (press device 24) in a state where the wrist unit 7is disposed outside the press devices 24, 25. Moreover, at thisposition, a workpiece W in the press device 24, such as sheet metalwhich has been subjected to one step of press machining, can be caughtand be removed from a mold (not shown) of the press device 24 by thetool S provided at the slider 19.

In this state, the swivel base 4, the first arm 5, and the second arm 6are moved like a pendulum to bring the wrist unit 7 close to the otherpress device (press device 25), the wrist unit 7 is operated to maintainthe attitude of the transfer tool 1, and the transfer tool 1 is operatedto move the two sliders 19, 20 relative to each other in such a way thatthe frame 18 and the workpiece W gripped by the tool S are inserted intothe other press device (press device 25). Also in this case, thetransfer tool 1 is moved along the press center line P, and thus, thetool S may be operated to release the transferred workpiece W and todrop the workpiece W into the mold of the other press device (pressdevice 25).

That is, the transfer tool 1 includes the strip-shaped frame 18, and hasa thickness dimension sufficiently smaller than that of the wrist unit7. Accordingly, the transfer tool 1 may be easily inserted even into asmall gap of a vertically opened mold in the press device 24, 25 to gripor release a workpiece W.

Particularly, in the case of transferring a workpiece W between thepress devices 24, 25, the efficiency of a pressing step is desired to beincreased by causing the tool S for gripping the workpiece W to enterimmediately after the mold of the press device 24, 25 starts to open,and to retract from the press device 24, 25 immediately before the moldcloses. Accordingly, the transfer tool 1 having a small thicknessdimension is suitable as a mechanism for entering into the press device24, 25.

Furthermore, the wrist unit 7 is moved along a straight track byrotation of the swivel base 4, swinging of the first arm 5, and linearmovement of the second arm 6, while maintaining constant attitude of thetransfer tool 1 by the wrist unit 7 having the three shafts J4, J5, J6,and thus, the transfer tool 1 may be moved on the same plane, and thereis an advantage that interference between each part of the press device24, 25 and the transfer tool 1 can be avoided.

Furthermore, by causing the second arm 6 to linearly move in thelongitudinal direction with respect to the first arm 5, the shape of theentire arm formed from the first arm 5 and the second arm 6 may beconstantly maintained to be substantially straight, and there is anadvantage that interference of each part of the first arm 5 and thesecond arm 6 with each part of the press device 24, 25 and peripheralequipments can be avoided.

Moreover, the transfer tool 1 horizontally moves the frame 18 by movingthe two sliders 19, 20 relative to each other in the horizontaldirection, and thus, by causing the movement direction of the frame 18to coincide with the transfer direction of the workpiece W, an advantagethat the workpiece W can be transferred at a high speed by the operationof the transfer tool 1, without greatly moving the wrist unit 7 at thetime of transfer of the workpiece W, may be achieved.

Moreover, with the articulated robot 30, attachment is performed withthe sixth axis line E of the wrist unit 7 being tilted, by the tiltedcoupling member 23, in the width direction of the frame 18 of thetransfer tool 1, and there is an advantage that each rotation shaft J4,J5, J6 of the wrist unit 7 can be prevented from being forcibly moved atthe time of causing the frame 18 of the transfer tool 1 to move at asubstantially horizontal attitude.

That is, by setting the frame 18 of the transfer tool 1 to be at asubstantially horizontal attitude by the tilted coupling member 23 evenin a state where each of the rotation shafts J4, J5, J6 of the wristunit 7 is arranged at an origin position, the rotation angle of eachrotation shaft J4, J5, J6 of the wrist unit 7 during transfer of aworkpiece W is not made great, and there is an advantage that the speedof transfer of a workpiece W can be increased.

Furthermore, with the transfer tool 1 according to the presentembodiment, of the two sliders 19, 20, the tool S is attached, via thedistal-end swing shaft 37, to the slider 20, which is disposed on theopposite side of the frame 18 from the slider 19 fixed to the sixthshaft J6 of the wrist unit 7, and thus, the angle of the tool S aroundthe axis line F along the width direction of the frame 18 may be changedby operation of the distal-end swing shaft 37.

Due to variations in the shape of the workpiece W to be pressed, thedirection of removal of the workpiece W from the mold of the pressdevice 24, 25 is not limited to a vertical direction. As shown in FIG.8, by operating the distal-end swing shaft 37 and tilting the tool S,the tilt of the tool S can be aligned with the direction of removal ofthe workpiece W without changing the attitude of the transfer tool 1.FIG. 8 shows a case where the tilted coupling member 23 is not provided.

As shown in FIG. 9, if the distal-end swing shaft 37 is not used, or ifthe distal-end swing shaft 37 is not provided, changing the tilt of thetool S causes the attitude of the transfer tool 1 to be changed bymovement of the position of the wrist unit 7 of the articulated robot30, and the possibility of interference of the second arm 6, the wristunit 7, and the transfer tool 1 with the press device 24, 25 andperipheral equipments is increased. A broken line in FIG. 9 indicates amovement range of the wrist unit 7 for gripping a workpiece W by thetool S.

That is, as shown in FIG. 9, by including the distal-end swing shaft 37,the transfer tool 1 according to the present embodiment can achieveadvantages that interference with the press device 24, 25 and peripheralequipments can be easily avoided, and that movement of the swivel base4, the first arm 5, the second arm 6, and the wrist unit 7 for changingthe angle of the tool S may be minimized to prevent an increase in thetransfer time.

Moreover, with the transfer tool 1 according to the present embodiment,the motor 42 for generating power for swinging the workpiece supportsection 36 around the axis line F is mounted on the slider 20 rotatablysupporting the workpiece support section 36, near the workpiece supportsection 36, and thus, driving does not have to be performed as in thepast by a belt (not shown), for driving the distal-end swing shaft,having a length two times the longitudinal dimension of the frame 18,and the workpiece support section 36 can be efficiently swung. As aresult, friction caused by driving by a belt can be reduced and powercan be efficiently used, and the motor 42 for driving the workpiecesupport section 36 can be miniaturized.

Moreover, because output of the motor 42 is transmitted to the shaft 38via the reducer 43 and the gears 44, 45, which are rigid mechanicalelements, fluctuations in load torque acting on the shaft 38 may beeasily detected based on a change in the current value of the motor 42.Accordingly, whether the tool S or the workpiece W has interfered withperipheral equipments or not can be detected with high accuracy, forexample. There is also an advantage that, compared with a belt fordriving the distal-end swing shaft, the frequency of maintenance can begreatly reduced.

Moreover, with the transfer tool 1 according to the present embodiment,the output shaft of the reducer 43 is coupled to the workpiece supportsection 36 not directly but via the pair of gears 44, 45, and thus, themotor 42 does not have to be coaxially disposed on the axis line F ofthe workpiece support section 36, and the workpiece support section 36may be extended on both sides of the frame 18 in the width direction andthe pair of interface portions 39, 40 may be provided on both ends.

Accordingly, as shown in FIG. 6, in the case where, in order to transfera relatively large workpiece W, the tool S and the workpiece W aredisposed in a manner extending on both sides of the frame 18 in thewidth direction, the tool S may be attached to the interface portions39, 40 disposed on both sides of the frame 18 in the width direction,and the frame 18 may be easily arranged approximately at the position ofthe center of gravity of the tool S and workpiece W. An advantage thattransfer may be performed while easily maintaining the weight balance ofthe large tool S and the large workpiece W may thus be achieved.

Furthermore, in the present embodiment, the pair of gears 44, 45 betweenthe output shaft of the reducer 43 and the workpiece support section 36have a reduction ratio by which the output of the reducer 43 istransmitted to the workpiece support section 36 after being reduced inthe speed of rotation, and thus, the output torque of the reducer 43 maybe amplified and transmitted to the workpiece support section 36.Therefore, the sizes and weights of the motor 42 and the reducer 43 maybe further reduced.

Additionally, in the present embodiment, the distal-end swing shaft 37includes the motor 42 which is disposed in parallel to the axis line Ffor swinging the shaft 38, and power from the motor 42 and the reducer43 is transmitted to the shaft 38 via the pair of gears 44, 45, but thisis not restrictive, and the motor 42 may be disposed intersecting withthe shaft 38 and power may be transmitted by a bevel gear. Moreover, thepower transmission section is not limited to the pair of gears 44, 45,which are spur gears, and may alternatively be a gear train formed froma plurality of gears.

Moreover, the reducer 43 may adopt a structure which allows sealing of alubricant by an independent sealing means so that lubrication isperformed separately from lubrication in the gearbox 47. This allows thereducer 43 to be easily replaced.

Moreover, instead of being integrally fixed to the shaft 38, theinterface portions 39, 40 on both ends of the shaft 38 may be a frictioncoupling 51 which is detachably fixed by friction to an outercircumferential surface of the rod-shaped shaft 38 by a wedge effect, asshown in FIG. 12. This allows use of interface portions 39, 40 which aresuitable for a tool S.

From the above-described embodiment, the following invention is derived.

An aspect of the present invention provides a transfer tool including asubstantially strip-shaped frame, a wrist-side slider to be attached toa wrist of a robot, provided on one side of the frame in a thicknessdirection in a manner capable of moving along a longitudinal directionof the frame, a workpiece-side slider provided on another side of theframe in the thickness direction in a manner capable of moving along thelongitudinal direction of the frame, and a distal-end swing shaftattached to the workpiece-side slider. The distal-end swing shaftincludes a workpiece support section that is for supporting a workpieceand that is supported by the workpiece-side slider in a manner capableof swinging around an axis line extending in a width direction of theframe, and an actuator that is attached to the workpiece-side slider andthat is for causing the workpiece support section to swing.

According to the present aspect, by causing the wrist-side slider andthe workpiece-side slider to move in a lengthwise direction of the framein a state where the wrist-side slider is fixed to a wrist of a robotand a workpiece is supported by the workpiece support section of thedistal-end swing shaft attached to the workpiece-side slider, theworkpiece may be transferred at a high speed in the longitudinaldirection of the frame, and also, the reach may be extended to theextent of a movable range of each slider and a stroke two times themovable range of each slider may be obtained.

Furthermore, by causing the workpiece support section to swing byoperation of the actuator of the distal-end swing shaft, the attitude ofa workpiece supported by the workpiece support section may be changedaround the axis line extending in the width direction of the frame.

In this case, the workpiece support section is driven by the actuatorfixed to the workpiece-side slider, and thus, the actuator and theworkpiece support section may be disposed close to each other, therebyeliminating the need for a long, low-rigidity timing belt fortransmitting power of the actuator to the workpiece support section.Accordingly, friction loss occurring at the timing belt may be greatlyreduced, and the power of the actuator may be efficiently transmitted tothe workpiece support section to drive the workpiece support sectionwith high accuracy, and also, fluctuations in load torque at thedistal-end swing shaft may be swiftly detected.

In the aspect described above, the actuator may include a motor, areducer for reducing speed of rotation of the motor, and a powertransmission section for transmitting output of the reducer to theworkpiece support section.

This allows a torque which is amplified by reduction in the speed ofrotation of the motor by the reducer to be transmitted to the workpiecesupport section by the power transmission section. Accordingly, the sizeand weight of the motor may be reduced.

Furthermore, in the aspect described above, the power transmissionsection may transmit the output of the reducer to the workpiece supportsection after reducing the output.

This allows the torque output from the reducer to be amplified andtransmitted also at the power transmission section, and thus, the sizeand weight of the reducer may be reduced.

Furthermore, in the aspect described above, the motor may be disposednon-coaxially with the axis line, and the workpiece support section mayinclude a shaft extending on both sides of the frame in the widthdirection, and a pair of interface portions provided on both ends of theshaft.

This allows a device, such as a hand for attaching/detaching aworkpiece, extending on both sides in the width direction with the frameat the center to be easily attached to the pair of interface portions onboth sides of the shaft and to be disposed with a good weight balance.By disposing the motor non-coaxially with the axis line of swinging ofthe workpiece support section, a structure where the shaft is extendedon both sides of the frame in the width direction may be easily adopted.

Moreover, in the aspect described above, the pair of interface portionsmay include attachment surfaces that are parallel to each other.

This eliminates the burden of having to perform angle alignment betweena device and each interface portion at the time of attaching a device tothe pair of interface portions.

REFERENCE SIGNS LIST

-   1 transfer tool-   7 wrist unit (wrist)-   18 frame-   19 slider (wrist-side slider)-   20 slider (workpiece-side slider)-   30 articulated robot (robot)-   36 workpiece support section-   37 distal-end swing shaft-   38 shaft-   39, 40 interface portion-   41 attachment surface-   42 motor (actuator)-   43 reducer (actuator)-   44 gear (drive gear, power transmission section, actuator)-   45 gear (driven gear, power transmission section, actuator)-   51 friction coupling (interface portion)-   F axis line

The invention claimed is:
 1. A transfer tool comprising: a substantiallystrip-shaped frame; a wrist-side slider to be attached to a wrist of arobot, provided on one side of the frame in a thickness direction in amanner capable of moving along a longitudinal direction of the frame; aworkpiece-side slider provided on another side of the frame in thethickness direction in a manner capable of moving along the longitudinaldirection of the frame; an actuator attached to the workpiece-sideslider, the actuator comprising a motor; a shaft attached to theworkpiece-side slider so as to extend in a width direction of the frame,the shaft being rotated by rotation of the motor; wherein the motor isdisposed non-coaxially with an axis line of the shaft; and a strutextending in the width direction of the frame, the strut being fixed oneach of both ends of the shaft and used for gripping a workpiece.
 2. Thetransfer tool according to claim 1, wherein the actuator includes areducer for reducing speed of rotation of the motor, and a powertransmission section for transmitting output of the reducer to theshaft.
 3. The transfer tool according to claim 2, wherein the powertransmission section transmits the output of the reducer to the shaftafter reducing the output.
 4. The transfer tool according to claim 1,further comprising a pair of interface portions, for fixing the strut,provided on both ends of the shaft.
 5. The transfer tool according toclaim 4, wherein the pair of interface portions include attachmentsurfaces that are parallel to each other.